1. Field of the Invention
The present invention relates to a printing apparatus which prints an image based on image data having undergone color correction processing.
2. Description of the Related Art
It has conventionally been known that the density and tint in color reproduction by a color printing apparatus are greatly affected by the individual characteristics of each printing apparatus, use conditions such as room temperature and the elapsed time, the type of paper serving as a printing medium, and the like. For this reason, the printing apparatus outputs test pattern data of a reference color onto a printing medium for use before outputting an actual image. Then, image data undergoes color correction based on color correction data which is the result of measuring the color of the output test pattern using a colorimeter. More specifically, color correction data read by the colorimeter is transmitted to a host apparatus (for example, PC) serving as an image output source. The host apparatus calculates a color correction parameter based on a comparison difference from an ideal value using a multi-dimensional lookup table. The host apparatus executes color correction for actual output image data using the calculated color correction parameter so that an output color in the printing apparatus coincides with a display color in the host apparatus. Then, the host apparatus transmits the actual output image data to the printing apparatus, and the printing apparatus outputs it, implementing color reproduction in output.
However, executing a series of operations for color correction in every image output which places importance on color reproduction wastes consumables, of which the type varies depending on the image forming method, such as ink for an inkjet method or toner for an electrophotographic method. Further, output and color measurement of a test pattern take a predetermined time, decreasing the use efficiency of the whole printing apparatus. To solve these problems, color correction data is stored in the printing apparatus together with time information. The same color correction data is used until the lapse of a predetermined time, a change of the use condition such as a change of room temperature, a change of the paper type, or the like. There is also proposed a print system in which color correction data is stored not in a printing apparatus but in a host apparatus which has output the color correction data (Japanese Patent Laid-Open No. 2003-345572).
In Japanese Patent Laid-Open No. 2003-345572, the printing apparatus stores information for specifying a host apparatus which has acquired color correction data. When another host apparatus requests color correction, the color correction data is acquired using the host specifying information from the host apparatus which exists on the same line and stores the color correction data. This technique can omit a series of operations for color correction, and implement color correction even in a host-based driven printing apparatus having a small storage area.
Recently, concern for the environment has led to a more prominent tendency to save energy. Popular printing apparatuses shift to a power saving state when they stand still for a predetermined time or more. Power is saved by, for example, stopping power to functional blocks except for the minimum number necessary to return to a normal operation state in response to only reception of data or a user operation. To hold the power saving state as long as possible, there is proposed even a printing apparatus in which a communication control unit singly responds to, for example, a periodical inquiry about the printing apparatus state from an application such as a status monitor in the host apparatus without returning the printing apparatus from the power saving state.
However, in the conventional technique, even when usable color correction data is stored in the printing apparatus, the printing apparatus needs to return from the power saving state upon receiving a color correction data acquisition request from the host apparatus. The printing apparatus needs to wait in the normal operation state and wastefully consumes power until the completion of transmitting color correction data to the host apparatus, and calculating a color correction parameter and performing color correction processing for output image data in the host apparatus.
Even if the host apparatus is configured to store color correction data, the printing apparatus stores host specifying information and thus needs to return to the normal operation state. In addition, the host apparatus which stores the color correction data needs to be active, too. In an environment where a plurality of printing apparatuses are connected to a plurality of host apparatuses, like a network interface, color correction data need to be stored by the number of printing apparatuses for respective paper types, increasing the data amount stored in the host apparatuses. When a plurality of host apparatuses store color correction data for respective paper types, they need to be active, and the whole print system enormously consumes power. It is therefore desirable to store color correction data in the printing apparatus.